Mitigation for the Construction and Operation of Libby Dam

PROJECT HISTORY
Montana Fish, Wildlife and Park’s (FWP) began to assess the effects of Libby Dam
operation on fish populations and lower trophic levels in 1982. This project established
relationship between reservoir operation and biological productivity, and incorporated the results
in the quantitative biological model LRMOD. The models and preliminary IRC’s (called
Biological Rule Curves) were first published in 1989 (Fraley et al. 1989), then refined in 1996
(Marotz et al. 1996). Integrated Rule Curves (IRC’s) were adopted by NPPC in 1994, and have
recently been implemented, to a large degree, in the federal Biological Opinion (BiOp) for white
sturgeon and bull trout (USFWS 2000). This project developed a tiered approach for white
sturgeon spawning flows balanced with reservoir IRC’s and the NOAA-Fisheries BiOp for
salmon and steelhead.The sturgeon tiered flow strategy was adopted by the White Sturgeon
Recovery Team in their Kootenai white sturgeon recovery plan (USFWS 1999) and later refined
in the USFWS 2000 BiOp.
A long-term database was established for monitoring populations of kokanee, bull trout,
westslope cutthroat trout, rainbow trout and burbot and other native fish species. Long-term
monitoring of zooplankton and trophic relationships was also established. A model was
calibrated to estimate the entrainment of fish and zooplankton through Libby Dam as related to
hydro-operations and use of the selective withdrawal, thermal control structure. Research on the
entrainment of fish through the Libby Dam penstocks began in 1990, and results were published
in 1996 (Skaar et al. 1996). The effects of dam operation on benthic macroinvertebrates in the
Kootenai River was also assessed (Hauer et al. 1997) for comparison with conditions measured
in the past (Perry and Huston 1983). The project identified important spawning and rearing
tributaries in the U.S. portion of the reservoir and began genetic inventories of species of special
concern. Research on the effects of operations on the river fishery using Instream Flow
Incremental Methodology (IFIM) techniques was initiated in 1992. Assessment of the effects of
river fluctuations on Kootenai River burbot fishery was examined in 1994 and 1995. IFIM
studies were also completed in Kootenai River below Bonners Ferry, Idaho, to determine
spawning area available to sturgeon at various river flows. Microhabitat data collection specific
to species and life-stage of rainbow trout and mountain whitefish has been incorporated into
suitability curves. River cross-sectional profiles, velocity patterns and other fisheries habitat
attributes were completed in 1997. Hydraulic model calibrations and incorporation of suitability
curves and modification of the model code were completed in 1999. The IFIM model is
currently being updated and frefined by Miller Ecological Consultants, Inc.
Montana FWP has completed several on-the-ground projects since beginning mitigation
activities since 1997. Highlights of these accomplishments are listed below for each year.
1997 – Montana FWP chemically rehabilitated Bootjack, Topless and Cibid Lakes (closed-basin
lakes) in eastern Lincoln County to remove illegally introduced pumpkinseeds and yellow perch
and re-establish rainbow trout and westslope cutthroat trout.
1998 - Montana FWP rehabilitated 200' of Pipe Creek stream bank in cooperation with a private
landowner to prevent further loss of habitat for bull trout and westslope cutthroat trout. Pipe
Creek is a primary spawning tributary to the Kootenai River.
1998 through 2000 - Montana FWP developed an isolation facility for the conservation of native
redband trout at the Libby Field Station. Existing ponds were restored and the inlet stream was
enhanced for natural outdoor rearing. Natural reproduction may be possible. Activities included
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